The invention relates to seats in general, and more particularly to improvements in seats which can be used with advantage in motor vehicles. Still more particularly, the invention relates to improvements in seats of the type wherein the occupant can be protected by a safety belt or seat belt to stand a better chance of surviving, remaining uninjured or suffering less serious injuries in the event of an accident.
It is known to connect one coupling element for the safety belt at the upper end of one lateral frame member for the back rest cushion of a seat in a motor vehicle. The belt extends from such coupling element to another coupling element which is located at the level of the base of the seat opposite the lateral frame member which carries the one coupling element. The other coupling element can constitute a buckle which can receive a latch plate at the free end of the belt. As a rule, the frame member which carries the one coupling element (such as a reel which is designed to automatically collect the belt as soon as the latch plate is disengaged from the buckle) is a hollow profile which is assembled of two C-shaped or U-shaped shells in order to be capable of standing pronounced stresses which develop when the belt is under tension during a collision or as a result of forward propulsion of the body of the occupant during abrupt deceleration or stoppage of the vehicle. The upper end portions of the lateral frame members of the back rest of the seat frame are normally connected to each other by a crossbar which also exhibits a hollow profile, normally a polygonal profile, and is assembled of several metallic shells having a C-shaped or U-shaped cross-sectional outline.
Such back rests are capable of standing pronounced deforming and breaking stresses, provided that their profiles are dimensioned accordingly, i.e., that their wall thickness is sufficient to enable the lateral frame member which carries the one coupling element to retain its shape in the event of a collision or under analogous adverse circumstances. This contributes to the cost and weight of the seat, and more particularly to the bulk, weight and cost of the frame portion which is to carry the cushion for the back of the occupant of the seat.